The invention relates to a radial press with a press axis and with a plurality of outer cam surfaces which are disposed at an angle to one another and have surface normals aimed at the press axis, and which are disposed in sets of two press yokes movable radially against one another by a driving system, the planes of symmetry of the cam surfaces disposed in the same press yoke running parallel to the drive direction, and having several outer cam follower bodies, each lying between two of the outer cam surfaces, for the radial advancement of press jaws toward the press axis.
Such radial presses serve for the shaping or machining of workpieces having rotationally symmetrical external surfaces, such as pipes, tubes, thimbles etc. An especially wide field of application of such radial presses is the manufacture of hoses by the radial pressing of hollow cylindrical hose sleeves, provided as a rule with an internal bead, onto a hose end having an armature of steel wire, from which the elastomeric outer layer has been removed. In the end of the hose in this case is a coupling piece consisting of metal, against which the hose end is to be pressed under high pressure by means of the sleeve. Such hose lines must be able to withstand pressures of up to 1,000 bar and more under fluctuating stress over a long period of time. Any failure of such a hose with a discharge of hydraulic fluid can lead to fatal injuries, and therefore the radial presses in question must satisfy stringent requirements.
The term, "rotationally symmetrical outside surfaces", is to be understood to mean workpiece shapes with circular cross sections and cross sections in the form of regular polygons, such as those to be found in hexagonal cross sections. The outer surfaces of the workpiece can be straight, barrel-shaped or stepped. Such workpiece surfaces can be provided for by shaping the press jaws accordingly.
Another problem is based on the fact that neither the press manufacturer nor the user can anticipate the numerous shapes of metal couplings for the hoses in question. A large number of the couplings are in the form of elbows, for example, and coupling parts with long tubular pieces are known. Such coupling units necessitate a great amount of free space on the back of the press facing away from the operator's side, and likewise a very short axial depth in the press. Both requirements militate against the design needs of such presses, in which high pressing forces and reaction forces must be reckoned with. Furthermore, the presses in question must be as small as possible and for many applications they must also be transportable without great complications, for example for use on large construction sites. Special machines have, as a rule, a large number of high-pressure hose lines which also have to be replaced and repaired in the field, by separating the hose from the still usable coupling parts. The re-use of the coupling parts is practiced even for the sake of reducing industrial waste.
A radial press of the kind described above pertains to the state of the art due to public use, and its principles of design and action will be further explained in a detailed description in conjunction with FIG. 1. At this point it will only be said that the press in question has a large and heavy one-piece press frame completely encompassing the hydraulic cylinder for reasons of strength.
German patent disclosure document OS 35 13 129 discloses a radial press with four hydraulic drivers disposed star-wise, in which twice the number of press jaws, namely eight, can be actuated synchronously by the interaction of four outer and four inner cam follower bodies. This press too has a large and heavy press frame, which is ring-like.
It is the object of the invention, on the other hand, to provide a radial press of the kind described above, which will be smaller and lighter, have an extremely short depth, and on the back of the press facing away from the operator's side, it will have virtually unlimited room both for the insertion of fittings with elbows and for the processing of fittings with long pipes and of endless tubing.
The solution of the problem is accomplished in accordance with the invention in the radial press described above in that the one press yoke is moved against the other press yoke by traction posts which are disposed parallel to the direction of action and pass through the guiding press yoke at the ends of the yoke outside of the yoke's cam faces, are affixed to the other, guided press yoke, and are connected on the other side of the guiding press yoke to a driver having a pulling action.
A radial press thus configured combines an extremely small size and especially small depth with low weight and an extremely simple construction.
The drivers with pulling action might be, for example, threaded spindles; it is especially advantageous, however, if a hydraulic jack could be associated with each traction post. Since the radial press does not require a circular press frame as in the state of the art, there is no need for components subject to traction and/or flexure to be mounted around the hydraulic jack, so that substantially larger piston faces can be used without interfering with a press frame, so that either the pressing force can be increased or the driving capacity of the hydraulic jack can be reduced. Further particulars on this will be set forth in the detailed description.
An especially advantageous design of such a press is characterized, pursuant to additional development, in that the press axis is horizontal, that the bottom, guiding press yoke is disposed on a platform beneath which the hydraulic jacks are in a case containing hydraulic fluid, and that the bottom press yoke and the hydraulic jacks are mounted on opposite sides of the platform.
In such a design the positive forces and reaction forces are directly engaged with one another and cancel one another within a minimum of space. Therefore it is not even necessary to provide the platform with any special rigidity.
The term, "platform," as used herein refers to all components which absorb the contrary forces of the press yoke and the hydraulic jack. In the simplest case it can be a horizontal steel plate serving as the cover or top of the case.
It is especially advantageous that each press yoke has an approximately parallelepipedal envelope surface with one long axis and two cam faces set at a right angle to one another and separated by a planar surface parallel to the long axis of the parallelepiped, the bisectors of the angle being parallel to the direction of the press action; that four outer cam follower bodies and four inner cam follower bodies are present, which alternate on the circumference; that the outer cam follower bodies lying above and below the press axis are supported motionless on the said planar surfaces of the press yokes; that the press yokes have additional planar boundary surfaces radially outside of the cam faces, which are parallel to one another and perpendicular to the direction of the press action, and that the bores in line with one another in pairs that are provided for two traction posts are brought through these planar boundary surfaces.
Additional advantageous configurations of the subject matter of the invention will be found in the secondary claims.